1. Field of the Invention
The invention relates to a reactor and a manufacturing method of the same. Incidentally, the reactor is a passive element that utilizes a coil, and is also referred to as “an inductor”.
2. Description of Related Art
A reactor may be employed in a circuit of a voltage converter or the like in a motor drive system of electric vehicles including hybrid vehicles. A large current is needed to drive a running motor. Therefore, a large current flows through the reactor as well, and the heat release value thereof is large. Thus, with a view to holding the heat release value small, a rectangular wire whose internal resistance is small is sometimes employed as a winding of a coil. In the case where the rectangular wire is employed, the rectangular wire is wound such that a wide face thereof is oriented in an axial direction of the coil. In other words, the rectangular wire is wound such that a narrow face thereof is oriented in a radial direction of the coil. Such a winding pattern is referred to as edgewise winding or vertical winding.
In order to further reduce the heat release value, it has been proposed to hold a radiator plate in contact with a lateral face of the coil, in addition to winding the rectangular wire edgewise (Japanese Patent Application Publication No. 2012-114122 (JP-2012-114122 A) and Japanese Patent Application Publication No. 2012-124401 (JP-2012-124401 A)).
Since the rectangular wire exhibits high rigidity, the radii of respective turns thereof may not be uniform. As a result, the outer position of the rectangular wire at each turn may be slightly displaced, and the area of contact with the radiator plate may be decreased. On the other hand, even if the coil is pressed from the other side of a coil lateral face intended to come into contact with the radiator plate, i.e., the contacting face, the contacting face (the coil lateral face that is intended to come into contact with the radiator plate) is not always sufficiently flattened due to low rigidity of the coil. Thus, in an art disclosed in Japanese Patent Application Publication No. 2012-114122 (JP-2012-114122 A), a plate is placed on the contacting face, and is pressed outward from inside the coil to flatten the contacting face. More details of the art disclosed in Japanese Patent Application Publication No. 2012-114122 (JP-2012-114122 A) are as follows.
In a reactor disclosed by Japanese Patent Application Publication No. 2012-114122 (JP-2012-114122 A), the rectangular wire is wound edgewise into a substantially rectangular shape, the entire coil is molded into a rectangular parallelepiped, and one lateral face thereof is brought into contact with the radiator plate. Hereinafter, among coil lateral faces, that which is intended to come into contact with the radiator plate will be referred to as the contacting face. Incidentally, a resinous insulator (bobbin) is arranged inside the coil. In order to uniformly flatten the contacting face, the bobbin is inserted through the coil, another plate is placed on the contacting face of the coil, and the bobbin is pressed from the other side of the contacting face at both ends of the coil in the axial direction thereof. Then, a tube portion of the bobbin is pressed outward (toward the contacting face side) from inside the coil, and the contacting face is uniformly flattened.
However, in the art disclosed in Japanese Patent Application Publication No. 2012-114122 (JP-2012-114122 A), the bobbin is divided into flange portions at both ends thereof (those portions which are opposed to the coil in the axial direction thereof respectively) and a window portion. Each of the flanges is provided with a protrusion portion that protrudes inward of the window portion and presses the window portion. In this manner, the art disclosed in Japanese Patent Application Publication No. 2012-114122 (JP-2012-114122 A) necessitates a complicated bobbin.